Multi-speed transmission

ABSTRACT

A transmission of the present invention has an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches and brakes. The torque transmitting devices are selectively engageable in combinations of at least three to establish at least nine forward speed ratios and at least one reverse speed ratio

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices, and more particularly to a transmission havingnine or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

In an aspect of the present invention a transmission is provided havingan input member, an output member, a first, second, third and fourthplanetary gear sets each having sun gears, carrier members and ringgears. The input member is continuously interconnected with the sun gearof the fourth planetary gear set and the carrier of the third planetarygear set and the ring gear of the second planetary gear set. The outputmember is selectively interconnected with the carrier member of thefirst planetary gear set or the ring gear of the third planetary gearset.

Additionally, a first interconnecting member continuously interconnectsthe sun gear of the first planetary gear set with the carrier of thesecond planetary gear set, a second interconnecting member continuouslyinterconnects the ring gear of the second planetary gear set with thecarrier member of the third planetary gear set, a third interconnectingmember continuously interconnects the sun gear member of the thirdplanetary gear set with the ring gear of the fourth planetary gear set,a fourth interconnecting member continuously interconnects the carrierof the third planetary gear set with the sun gear member of the fourthplanetary gear set and a fifth interconnecting member continuouslyinterconnects the ring gear of the first planetary gear set with astationary member.

Further, a first torque transmitting device is selectively engageable tointerconnect the ring gear member of the third planetary gear set withthe output member, a second torque transmitting device is selectivelyengageable to interconnect the carrier member of the second planetarygear set with sun gear of the third planetary gear set and the ring gearof the fourth planetary gear set, a third torque transmitting device isselectively engageable to interconnect the sun gear of the secondplanetary gear set with the ring gear of the fourth planetary gear set,a fourth torque transmitting device is selectively engageable tointerconnect the carrier member of the first planetary gear set with theoutput member, a fifth torque transmitting device is selectivelyengageable to interconnect the carrier member of the fourth planetarygear set with the stationary member and a sixth torque transmittingdevice is selectively engageable to interconnect the sun gear of thesecond planetary gear set with the stationary member. The torquetransmitting devices are selectively engageable in combinations of atleast three to establish at least nine forward speed ratios and at leastone reverse speed ratio between the input member and the output member.

It is thus an object of the present invention to provide a transmissionhaving four planetary gear sets.

It is a further object of the present invention to provide atransmission having nine forward speeds and at least one reverse.

It is a still further object of the present invention to provide atransmission having four planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of a nine speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the nine speed automatic transmission of the present inventionhas an arrangement of permanent mechanical connections between theelements of the four planetary gear sets. A first component or elementof a first planetary gear set is permanently coupled to a ground or astationary member. A third component or element of the first planetarygear set is permanently coupled to a second component or element of asecond planetary gear set. A first component or element of the secondplanetary gear set is permanently coupled to a second component orelement of a third planetary gear set. A second component or element ofthe third planetary gear set is permanently coupled to a first componentor element of a fourth planetary gear set. Finally, a third component orelement of a third planetary gear set is permanently coupled to a thirdcomponent or element of a fourth planetary gear set.

Referring now to FIG. 1, an embodiment of a nine speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. If the device is abrake, one set of the fingers is grounded. Further explanation of theformat, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input member 12 is coupled to the first node 20A of the fourthplanetary gear set 20. The first node 14A of the first planetary gearset 14 is coupled to a stationary member or the transmission housing 50.The third node 14C of the first planetary gear set 14 is coupled to thesecond node 16B of the second planetary gear set 16. The first node 16Aof the second planetary gear set 16 is coupled to the second node 18B ofthe third planetary gear set 18. The second node 18B of the thirdplanetary gear set 18 is coupled to the first node 20A of the fourthplanetary gear set 20. The third node 18C of the third planetary gearset 18 is coupled to the third node 20C of the fourth planetary gear set20.

A first clutch 26 selectively connects the first node 18A of the thirdplanetary gear set 18 with the output shaft or member 22. A secondclutch 28 selectively connects the second node 16B of the secondplanetary gear set 16 with the third node 18C of the third planetarygear set 18. A third clutch 30 selectively connects the third node 16Cof the second planetary gear set 16 with the third node 18C of the thirdplanetary gear set 18. A fourth clutch 32 selectively connects thesecond node 14B of the first planetary gear set 14 with the output shaftor member 22. A first brake 34 selectively connects the second node 20Bof the fourth planetary gear set 20 with a stationary element or atransmission housing 50. A second brake 36 selectively connects thethird node 16C of the second planetary gear set 16 with the stationaryelement or the transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brakes, and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aring gear member 14A and a planet gear carrier member 14B that rotatablysupports a set of planet gears 14D (only one of which is shown). Theplanet gears 14D are each configured to intermesh with both the sun gearmember 14C and the ring gear member 14A. The sun gear member 14C isconnected for common rotation with a first shaft or interconnectingmember 42. The ring gear member 14A is connected to a stationary member50 that prevents ring gear member 14A from rotating relative to member50. The planet carrier member 14B is connected for common rotation withfor common rotation with a second shaft or interconnecting member 44.

The planetary gear set 16 includes a sun gear member 16C, a ring gearmember 16A and a planet gear carrier member 16B that rotatably supportsa set of planet gears 16D (only one of which is shown). The planet gears16D are each configured to intermesh with both the sun gear member 16Cand the ring gear member 16A. The sun gear member 16C is connected forcommon rotation with a third shaft or interconnecting member 46. Thering gear member 16A is connected for common rotation with a fourthshaft or interconnecting member 48. The planet carrier member 16B isconnected for common rotation with the first interconnecting member 42and a fifth interconnecting member 52.

The planetary gear set 18 includes a sun gear member 18C, a ring gearmember 18A and a planet gear carrier member 18B that rotatably supportsa set of planet gears 18D (only one of which is shown). The set ofplanet gears 18D are each configured to intermesh with both the sun gearmember 18C and the ring gear member 18A. The sun gear member 18C isconnected for common rotation with a sixth shaft or interconnectingmember 54. The ring gear member 18A is connected for common rotationwith a seventh shaft or interconnecting member 56. The planet carriermember 18B is connected for common rotation with an eighth shaft orinterconnecting member 58 and with the fourth shaft or interconnectingmember 48.

The planetary gear set 20 includes a sun gear member 20A, a ring gearmember 20C and a planet gear carrier member 20B that rotatably supportsa set of planet gears 20D (only one of which is shown). The set ofplanet gears 20D are each configured to intermesh with both the sun gearmember 20A and ring gear member 20C. The sun gear member 20A isconnected for common rotation with the eighth shaft or interconnectingmember 58 and with the input shaft or member 12. The ring gear member20C is connected for common rotation with the sixth shaft orinterconnecting member 54. The planet carrier member 20B is connectedfor common rotation with a ninth shaft or interconnecting member 60.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or the clutches 26, 28, 30, 32 andthe brakes 34 and 36 allow for selective interconnection of the shaftsor interconnecting members, members of the planetary gear sets and thehousing. For example, the first clutch 26 is selectively engageable toconnect the output shaft or member 22 with the seventh shaft orinterconnecting member 56. The second clutch 28 is selectivelyengageable to connect the fifth shaft or interconnecting member 52 withthe sixth shaft or interconnecting member 54. The third clutch 30 isselectively engageable to connect the third shaft or interconnectingmember 46 with the ring gear member 20C. The fourth clutch 32 isselectively engageable to connect the second shaft or interconnectingmember 44 with the output shaft or member 22. The first brake 34 isselectively engageable to connect the ninth shaft or interconnectingmember 60 with a stationary element or the transmission housing 50 inorder to prevent the tenth shaft or interconnecting member 60 fromrotating relative to the transmission housing 50. The second brake 36 isselectively engageable to connect the third shaft or interconnectingmember 46 with a stationary element or the transmission housing 50 inorder to prevent the third shaft or interconnecting member 46 fromrotating relative to the transmission housing 50.

Referring now to FIGS. 2 and 3, the operation of the embodiment of thenine speed transmission 10 will be described. It will be appreciatedthat the transmission 10 is capable of transmitting torque from theinput shaft or member 12 to the output shaft or member 22 in at leastnine forward speed or torque ratios and at least one reverse speed ortorque ratio with a triple overdrive. Each forward and reverse speed ortorque ratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,third clutch 30, fourth clutch 32, first brake 34 and second brake 36),as will be explained below. FIG. 3 is a truth table presenting thevarious combinations of torque-transmitting elements that are activatedor engaged to achieve the various gear states. Actual numerical gearratios of the various gear states are also presented although it shouldbe appreciated that these numerical values are exemplary only and thatthey may be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmission 10. An exampleof the gear ratios that may be obtained using the embodiments of thepresent invention are also shown in FIG. 3. Of course, other gear ratiosare achievable depending on the gear diameter, gear teeth count and gearconfiguration selected.

To establish reverse gear, the second clutch 28, the fourth clutch 32and the first brake 34 are engaged or activated. The second clutch 28connects connect the fifth shaft or interconnecting member 52 with thesixth shaft or interconnecting member 54. The fourth clutch 32 connectsthe second shaft or interconnecting member 44 with the output shaft ormember 22. The first brake 34 connects the ninth shaft orinterconnecting member 60 with a stationary element or the transmissionhousing 50 in order to prevent the ninth shaft or interconnecting member60 from rotating relative to the transmission housing 50. Likewise, thenine forward ratios are achieved through different combinations ofclutch and brake engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmission 10 assumes, first of all,that all the clutches and brakes not specifically referenced in a givengear state are inactive or disengaged and, second of all, that duringgear shifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the third member of the first planetary gear set withthe second member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the first member ofthe second planetary gear set with the second member of the thirdplanetary gear set; a third interconnecting member continuouslyinterconnecting the second member of the third planetary gear set withthe first member of the fourth planetary gear set; a fourthinterconnecting member continuously interconnecting the third member ofthe third planetary gear set with the third member of the fourthplanetary gear set; a fifth interconnecting member continuouslyinterconnecting the first member of the first planetary gear set with astationary member; and six torque transmitting devices selectivelyengageable to interconnect one of the first, second, and third memberswith at least one other of the first members, second members, thirdmembers, and a stationary member, and wherein the torque transmittingdevices are selectively engageable in combinations of at least three toestablish at least nine forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 2. Thetransmission of claim 1 wherein a first of the six torque transmittingdevices is selectively engageable to interconnect the first member ofthe third planetary gear set with the output member.
 3. The transmissionof claim 2 wherein a second of the six torque transmitting devices isselectively engageable to interconnect the second member of the secondplanetary gear set with at least one of the third member of the thirdplanetary gear set and the third member of the fourth planetary gearset.
 4. The transmission of claim 3 wherein a third of the six torquetransmitting devices is selectively engageable to interconnect the thirdmember of the second planetary gear set with at least one of the thirdmember of the third planetary gear set and the third member of thefourth planetary gear set.
 5. The transmission of claim 4 wherein afourth of the six torque transmitting devices is selectively engageableto interconnect the second member of the first planetary gear set withthe output member.
 6. The transmission of claim 5 wherein a fifth of thesix torque transmitting devices is selectively engageable tointerconnect the second member of the fourth planetary gear set with thestationary member.
 7. The transmission of claim 6 wherein a sixth of thesix torque transmitting devices is selectively engageable tointerconnect the third member of the second planetary gear set with thestationary member.
 8. The transmission of claim 1 wherein the thirdmember of the first planetary gear set, the third member of the secondplanetary gear set, the third member of the third planetary gear set andthe first member of the fourth planetary gear set are sun gears, thesecond member of the first planetary gear set, the second member of thesecond planetary gear set, the second member of the third planetary gearset and the second member of the fourth planetary gear set are carriermembers and the first member of the first planetary gear set, firstmember of the second planetary gear set, the first member of the thirdplanetary gear set and the third member of the fourth planetary gear setare ring gears.
 9. The transmission of claim 1 wherein the input memberis continuously interconnected with at least one of the first member ofthe fourth planetary gear set and the second member of the thirdplanetary gear set.
 10. The transmission of claim 1 wherein two of thesix torque transmitting devices are brakes and four of the six torquetransmitting devices are clutches.
 11. The transmission of claim 1wherein the stationary member is a transmission housing.
 12. Atransmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members, wherein the input member is continuouslyinterconnected with at least one of the first member of the fourthplanetary gear set and the second member of the third planetary gearset; a first interconnecting member continuously interconnecting thethird member of the first planetary gear set with the second member ofthe second planetary gear set; a second interconnecting membercontinuously interconnecting the first member of the second planetarygear set with the second member of the third planetary gear set; a thirdinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the first member of the fourthplanetary gear set; a fourth interconnecting member continuouslyinterconnecting the third member of the third planetary gear set withthe third member of the fourth planetary gear set; a fifthinterconnecting member continuously interconnecting the first member ofthe first planetary gear set with a stationary member; a first torquetransmitting device selectively engageable to interconnect the firstmember of the third planetary gear set with the output member; a secondtorque transmitting device selectively engageable to interconnect thesecond member of the second planetary gear set with at least one of thethird member of the third planetary gear set and the third member of thefourth planetary gear set; a third torque transmitting deviceselectively engageable to interconnect the third member of the secondplanetary gear set with at least one of the third member of the thirdplanetary gear set and the third member of the fourth planetary gearset; a fourth torque transmitting device selectively engageable tointerconnect the second member of the first planetary gear set with theoutput member; and a fifth torque transmitting device selectivelyengageable to interconnect the second member of the fourth planetarygear set with the stationary member; and a sixth torque transmittingdevice selectively engageable to interconnect the third member of thesecond planetary gear set with the stationary member, and wherein thetorque transmitting devices are selectively engageable in combinationsof at least three to establish at least nine forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.
 13. The transmission of claim 12 wherein the third member of thefirst planetary gear set, the third member of the second planetary gearset, the third member of the third planetary gear set and the firstmember of the fourth planetary gear set are sun gears, the second memberof the first planetary gear set, the second member of the secondplanetary gear set, the second member of the third planetary gear setand the second member of the fourth planetary gear set are carriermembers and the first member of the first planetary gear set, firstmember of the second planetary gear set, the first member of the thirdplanetary gear set and the third member of the fourth planetary gear setare ring gears.
 14. The transmission of claim 12 wherein the stationarymember is a transmission housing.
 15. A transmission comprising: aninput member; an output member; first, second, third and fourthplanetary gear sets each having sun gears, carrier members and ringgears, wherein the input member is continuously interconnected with atleast one of the sun gear member of the fourth planetary gear set andthe carrier member of the third planetary gear set; a firstinterconnecting member continuously interconnecting the sun gear memberof the first planetary gear set with the carrier member of the secondplanetary gear set; a second interconnecting member continuouslyinterconnecting the ring gear member of the second planetary gear setwith the carrier member of the third planetary gear set; a thirdinterconnecting member continuously interconnecting the carrier memberof the third planetary gear set with the sun gear member of the fourthplanetary gear set; a fourth interconnecting member continuouslyinterconnecting the sun gear member of the third planetary gear set withthe ring gear member of the fourth planetary gear set; a fifthinterconnecting member continuously interconnecting the ring gear memberof the first planetary gear set with a stationary member; a first torquetransmitting device selectively engageable to interconnect the ring gearmember of the third planetary gear set with the output member; a secondtorque transmitting device selectively engageable to interconnect thecarrier member of the second planetary gear set with at least one of thesun gear member of the third planetary gear set and the ring gear memberof the fourth planetary gear set; a third torque transmitting deviceselectively engageable to interconnect the sun gear member of the secondplanetary gear set with at least one of the sun gear member of the thirdplanetary gear set and the ring gear member of the fourth planetary gearset; a fourth torque transmitting device selectively engageable tointerconnect the carrier member of the first planetary gear set with theoutput member; and a fifth torque transmitting device selectivelyengageable to interconnect the carrier member of the fourth planetarygear set with the stationary member; and a sixth torque transmittingdevice selectively engageable to interconnect the sun gear member of thesecond planetary gear set with the stationary member, and wherein thetorque transmitting devices are selectively engageable in combinationsof at least three to establish at least nine forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.
 16. The transmission of claim 15 wherein the stationary memberis a transmission housing.